Biomolecule microarrays are widely used as tools in high throughput technologies, including gene expression analysis, genotyping, nucleic acid analysis, nucleic acid sequencing, mutation analysis, protein and peptide analysis, and screening of potential drugs. Such microarrays are also increasingly used as combinatorial chemistry platforms for drug development and manufacturing.
Microarrays are generally formed on a surface of a glass, metal, plastic, or other substrate, with the substrate surface being functionalized or otherwise rendered capable of binding to biomolecules of interest. The modification of a substrate surface with a thin polyelectrolyte film is a common technique to prepare or treat the surface for subsequent binding of cells, nucleic acids, peptides, proteins, or other biomolecules thereon. The polyelectrolyte, which may be a polyanionic and/or polycationic material, is typically applied to a substrate by dip coating in an aqueous solution of the polyelectrolyte, with the polyelectrolyte binding to the substrate surface via electrostatic interactions. Biomolecules may then be attached to the polyelectrolyte coating via electrostatic interaction, “semi-covalent” or covalent bonding to functional groups on the coating, or other techniques. The polyelectrolyte coating will generally carry a large amount of charge, and may also be treated or passivated chemically prior to use as a research tool.
The use of a polyelectrolyte film in the above manner for anchoring biomolecules to a substrate is attractive due to ease of manufacturing, compatibility with a wide range of glass, metal and metal oxide substrate surfaces, and versatility with respect to a variety of attachable biomolecules. However, the relatively weak interaction between the polyelectrolyte and the underlying substrate surface can result in introduction of defects in a microarray during manufacture and/or use. Particularly, in the case of nucleic acid microarrays, the stresses associated with hybridization of polynucleotide analytes with nucleic acid probes on the array can result in de absorption of the polyelectrolyte from the substrate. Damage from such deabsorption can interfere with hybridization at the damaged portions of the array, cause errors in the optical characterization or readout of the array, or cause other problems that lead to incorrect data or results and which render the microarrays unusable.
There is accordingly a need for a method of securely bonding or stabilizing a polyelectrolyte coating to a substrate surface that provides for easy manufacture of robust, defect-free microarrays of various types of surface displayed entities of interest. The present invention satisfies these needs, as well as others, and generally overcomes the deficiencies found in the background art.
Relevant Literature
U.S. Patents of interest include: U.S. Pat. Nos. 5,250,613; 5,629,213; 5,807,522; and 6,110,426. Also of interest is WO 00/65352. See also: Decher et al., Current Opinion in Colloid and Interface Science 1998, 3, 32-39; and Diederich et al., Advances in Biophysics 1996, 34, 205-230.